After decades of fierce opposition to the use of all contraception, the
pontiff will end the Catholic Church's absolute ban on the use of condoms.

He will say that it is acceptable to use a prophylactic when the sole intention is to "reduce the risk of infection" from Aids.

While he will restate the Catholic Church's staunch objections to contraception because it believes it interferes with the creation of life, he will argue that using a condom to preserve life and avoid death can be a responsible act – even outside marriage.

Asked whether "the Catholic Church is not fundamentally against the use of condoms," he replies: "It of course does not see it as a real and moral solution.

"In certain cases, where the intention is to reduce the risk of infection, it can nevertheless be a first step on the way to another, more humane sexuality."

He will stress that abstinence is the best policy in fighting the disease, but accept that in some circumstances it is better for a condom to be used if it protects human life.

"There may be justified individual cases, for example when a male prostitute uses a condom, where this can be ... a first bit of responsibility, to redevelop the understanding that not everything is permitted and that one may not do everything one wishes.

"But it is not the proper way to deal with the horror of HIV infection."

The groundbreaking announcement will come in a book to be published by the Vatican next week based on the first face-to-face interview given by a Pope.

In the interview, he admits he was stunned by the sex abuse scandal that has engulfed the Catholic Church and raises the possibility of the circumstances under which he would consider resigning.

Most significant, however, are his comments on condoms, which represents the first official relaxation in the Church's attitude on the issue after growing calls from cardinals for the Vatican to adopt a more humane approach to stopping the spread of HIV.

Although the Pope's ruling is aimed specifically to stop people infecting their partners, particularly in Africa where the disease is most prevalent,

it will inevitably be seized upon by liberal Catholics in Britain who oppose the Church's long-standing stance against contraception.

High-profile Catholics including Cherie Blair have stated publicly that they use birth control.

The move by Pope Benedict is particularly surprising because he caused controversy last year by suggesting condom use could actually worsen the problem of Aids in Africa.

He described the epidemic in the continent as "a tragedy that cannot be overcome by money alone, that cannot be overcome through the distribution of condoms, which even aggravates the problems".